Cells in the nervous system

What is the function of dendrites?

Receive information and carry it to the cell body

In which direction does information travel through dendrites?

Towards the cell body

What is the cell body?

Region containing the nucleus and organelles

What is the axon hillock?

Region where action potentials are initiated

What are synaptic vesicles?

Vesicles containing neurotransmitters

Where are synaptic vesicles found?

Synaptic terminals

Why are some axons myelinated?

To increase transmission speed

How does myelination increase transmission speed?

By allowing saltatory conduction

What is saltatory conduction?

Action potentials jump between Nodes of Ranvier

Why is saltatory conduction faster than smooth conduction?

Depolarisation only occurs at nodes

Why doesn't depolarisation travel down the entire axon in myelinated neurons?

Myelin insulates the axon between nodes

What is the disadvantage of myelination?

It requires energy

Do all neurons need myelination?

No

Which neurons are most likely to be myelinated?

Neurons with long axons or requiring rapid transmission

How does axon diameter affect transmission speed?

Larger diameters increase speed

Which axons conduct signals fastest?

Large diameter myelinated axons

Why do neurons have different structures?

To suit different functions

What is an anaxonic neuron?

Neuron with many dendrites and no axon

How many processes does an anaxonic neuron have?

More than two

What is a bipolar neuron?

Neuron with two processes separated by the cell body

Where are bipolar neurons commonly found?

Sensory systems such as the retina

What is a unipolar neuron?

Neuron with one long process and an off-centre cell body

What is a multipolar neuron?

Neuron with many dendrites and one axon

Which neuron type is most common in the CNS?

Multipolar neuron

What are glial cells?

Support cells of the nervous system

What is the main role of glial cells?

Support and maintain neural function

What are ependymal cells?

Glial cells lining ventricles and the central canal

Where are ependymal cells found?

Brain ventricles and spinal cord central canal

What do ependymal cells produce?

Cerebrospinal fluid

What do ependymal cells do with cerebrospinal fluid?

Produce, circulate and monitor it

What are astrocytes?

Supportive glial cells in the CNS

What is the role of astrocytes in the blood-brain barrier?

Help maintain it

How do astrocytes support neurons?

Provide structural support

What do astrocytes regulate?

Ions, nutrients and dissolved gases

What do astrocytes do with neurotransmitters?

Absorb and recycle them

What type of tissue can astrocytes form?

Scar tissue

What are oligodendrocytes?

Myelin-producing glial cells of the CNS

What is the function of oligodendrocytes?

Myelinate CNS axons

Why are oligodendrocytes important?

Allow rapid information transmission

What additional role do oligodendrocytes have?

Provide structural framework

What are microglia?

Immune cells of the CNS

What is the function of microglia?

Remove debris, waste and pathogens

How do microglia remove pathogens?

By phagocytosis

Why are microglia important?

Maintain brain health

What do microglia continuously do?

Monitor the neural environment

What are microglia often called?

The macrophages of the brain

What are Schwann cells?

Glial cells that myelinate axons in the PNS

What is the role of Schwann cells?

Increase action potential conduction speed

Where are Schwann cells found?

Surrounding PNS axons

What are satellite cells?

Glial cells surrounding neuron cell bodies in ganglia

Where are satellite cells found?

PNS ganglia

What do satellite cells regulate?

O2, CO2, nutrient and neurotransmitter concentrations

What is Wallerian degeneration?

Programmed breakdown of an axon and myelin distal to injury

When does Wallerian degeneration occur?

After nerve injury

Which part of the neuron degenerates in Wallerian degeneration?

The axon and myelin downstream of the injury